A conventional thin-film solar cell module as a thin-film photoelectric conversion module includes thin-film solar battery cells each of which has a transparent electrode layer, a thin-film semiconductor layer as a photoelectric conversion layer, and a reflection conductive film as a back-surface electrode layer sequentially formed at one surface side of a substrate and generates photovoltaic power in the thin-film semiconductor layer by using light incident from the other surface side of the substrate, for example. A plurality of thin-film solar battery cells are electrically connected in series in a state that the thin-film solar battery cells are arranged at a predetermined distance between adjacent cells, thereby forming a thin-film solar cell module. Photoelectric conversion layers between adjacent thin-film solar battery cells are electrically isolated.
The thin-film solar cell module described above is manufactured in the following method. First, on a translucent insulating substrate on a surface of which a transparent electrode layer that has a texture structure having an uneven surface made of transparent conductive oxide (TCO) such as tin oxide (SnO2) and zinc oxide (ZnO) is formed, the transparent electrode layer is processed in a stripe shape by disconnecting and removing by laser irradiation. The texture structure has a function of scattering sunlight incident to the thin-film solar cells and of increasing light utilization efficiency in thin-film semiconductor layers.
Next, a thin-film semiconductor layer for photoelectric conversion made of a material such as amorphous silicon is formed on the transparent electrode layer by a plasma CVD (chemical vapor deposition) method or the like. Thereafter, at a position different from a position where the transparent electrode layer is disconnected, the thin-film semiconductor layer is processed in a stripe shape by disconnecting and removing by laser irradiation.
Next, a back-surface electrode layer made of a light-reflective metal is formed on the thin-film semiconductor layer by a sputtering method or the like. Thereafter, at a position different from a position where the transparent electrode layer is disconnected, the back-surface electrode layer is again disconnected and removed by laser irradiation to process the back-surface electrode layer in a stripe shape.
According to such a thin-film solar cell module, a current leakage on a processed surface of a thin-film semiconductor layer as a photoelectric conversion layer becomes a problem. That is, the thin-film semiconductor layer is processed by removing a film by irradiating laser beams as described above. At this time, when the laser beam strength is low, a processed film is not completely blown off, and a short-circuit failure occurs due to a residue of the film between an electrode of a transparent electrode layer of one thin-film solar cell and an electrode of a back-surface electrode layer of this thin-film solar cell. On the other hand, when the laser beam strength is high, no residue of film is generated, but a sidewall as a processed surface end of the thin-film semiconductor layer is molten and crystallized. The crystallized sidewall has higher electric conductivity than that of the inside of a thin-film semiconductor, and thus a short-circuit failure occurs between a transparent electrode layer of a thin-film solar cell and a back-surface electrode layer of this thin-film solar cell. As a result, photoelectric conversion efficiency is degraded and thus power generation efficiency is degraded.
To solve the above problems, for example, there has been proposed a technique of suppressing a current leakage by achieving a process that does not generate any residue even when laser beams having low strength are irradiated, by forming a film that has different crystallinity at only a position corresponding to a laser-processed portion of a thin-film semiconductor layer by using a plasma CVD device having cyclical convexes in an anode electrode (see, for example, Patent Literature 1).